Download Classify each triangle as acute, equiangular, obtuse, or right. 15

4-1 Classifying Triangles
Classify each triangle as acute, equiangular, obtuse, or right.
15. SOLUTION: One angle of the triangle measures 115, so it is a obtuse angle. Since the triangle has an obtuse angle, it is an obtuse
triangle.
ANSWER: obtuse
16. SOLUTION: The triangle has three acute angles that are not all equal. It is an acute triangle.
ANSWER: acute
17. SOLUTION: One angle of the triangle measures 90, so it is a right angle. Since the triangle has a right angle, it is a right triangle.
ANSWER: right
18. SOLUTION: Since all the angles are congruent, it is a equiangular triangle.
ANSWER: equiangular
If point C is the midpoint of
isosceles, or scalene.
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30. and point E is the midpoint of
, classify each triangle as equilateral,
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SOLUTION: Since all the angles are congruent, it is a equiangular triangle.
ANSWER: Triangles
4-1 Classifying
equiangular
If point C is the midpoint of
isosceles, or scalene.
and point E is the midpoint of
, classify each triangle as equilateral,
30. SOLUTION: In
, all the sides are of different lengths.
So, it is scalene.
ANSWER: scalene
32. SOLUTION: Here, E is the midpoint of
. So, DE = EF = 5.
Also by the Segment Addition Postulate, DF = DE + EF = 10.
In
, DF = 10 and AF = 10. The triangle
has two congruent sides. So, it is isosceles.
ANSWER: isosceles
35. SOLUTION: Here, C is the midpoint of
. So, BC = CD = 4.
Also by Segment Addition Postulate, BC = BC + CD = 8.
In
, AB = 8, BD = 8, and AD = 8. All the sides are congruent in
. So, it is equilateral.
ANSWER: equilateral
36. ALGEBRA Find x and the length of each side if
is an isosceles triangle with SOLUTION: Here,
By the definition of congruence,
Substitute.
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.
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Also by Segment Addition Postulate, BC = BC + CD = 8.
In
, AB = 8, BD = 8, and AD = 8. All the sides are congruent in
. So, it is equilateral.
ANSWER: Triangles
4-1 Classifying
equilateral
36. ALGEBRA Find x and the length of each side if
is an isosceles triangle with SOLUTION: Here,
By the definition of congruence,
Substitute.
Substitute
.
in AB, BC, and CA.
ANSWER: x = 7; AB = 7, BC = 7, CA = 4
CCSS PRECISION Classify each triangle in the figure by its angles and sides.
41. SOLUTION: eSolutions
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In the figure,
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.
ANSWER: Triangles
4-1 Classifying
x = 7; AB = 7, BC = 7, CA = 4
CCSS PRECISION Classify each triangle in the figure by its angles and sides.
41. SOLUTION: In the figure,
.
has two congruent sides and an obtuse angle. So, it is an isosceles obtuse triangle.
ANSWER: isosceles obtuse
COORDINATE GEOMETRY Find the measures of the sides of
sides.
43. X(–5, 9), Y(2, 1), Z(–8, 3)
and classify each triangle by its SOLUTION: Graph the points on a coordinate plane.
Use the Distance Formula to find the lengths of
.
has endpoints X(–5, 9) and Y(2, 1).
Substitute.
has endpoints Y(2, 1) and Z(–8, 3).
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Substitute.
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4-1 Classifying Triangles
has endpoints Y(2, 1) and Z(–8, 3).
Substitute.
has endpoints X(–5, 9) and Z(–8, 3).
Substitute.
No two sides are congruent. So, it is scalene.
ANSWER: scalene; XZ =
XY =
YZ =
ALGEBRA For each triangle, find x and the measure of each side.
50. is isosceles with
, JK = 4x – 1, KL = 2x + 5, and LJ = 2x – 1.
SOLUTION: Here,
.
By the definition of congruence,
Substitute.
Substitute
in JK, KL, and LJ.
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.
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No two sides are congruent. So, it is scalene.
ANSWER: 4-1 Classifying
scalene; XZ Triangles
=
XY =
YZ =
ALGEBRA For each triangle, find x and the measure of each side.
50. is isosceles with
, JK = 4x – 1, KL = 2x + 5, and LJ = 2x – 1.
SOLUTION: Here,
.
By the definition of congruence,
Substitute.
Substitute
.
in JK, KL, and LJ.
ANSWER: x = 3; JK = 11, KL = 11, LJ = 5
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